Enthalpy and Entropy

What is the symbol for entropy?

• H

• G

• S

• E

Entropy is a measure of

• accuracy

• precision

• the disorder of a system

• the attraction of a nucleus for an electron

Which of these reactions shows a DECREASE in entropy?

• CaCO₃(s) → CaO(s) + CO₂(g)

• 3O₂(g) → 2O₃(g)

• 2NH₃(g) → 3H₂(g) + N₂(g)

• C₆H₆(l) → C₆H₆(g)

Entropy increases from solid, liquid to gas. Why?

• Molecular disorder increases
• Molecular randomness decreases
• Molecules are more energetic
• Molecules are more reactive

Which represents a decrease in entropy?

• sublimation of CO₂

• boiling water

• condensation of steam on cold glass

• NaCl dissolving in water

Spontaneous reactions are driven by

• increasing enthalpy and increasing entropy.
• decreasing enthalpy and decreasing entropy.
• increasing enthalpy and decreasing entropy.
• decreasing enthalpy and increasing entropy.

What is enthalpy?

• .a) Energy stored in the movement of molecules in a substance

• b) The opposite of temperature

• c) The temperature of a molecule

• d) Energy stored in the chemical bonds in a substance

Tags

NGSS.HS-PS1-4

 

A reaction that gives out energy to the surroundings causes the surroundings ....

• a. temperature to drop

  temperature to rise

  temperature to remain constant

  temperature to vary

• b. emperature to rise

• c. temperature to remain constant

• d. temperature to vary

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

What does all our work, provides all our heat, can be stored to use later, and never, ever goes away?

• enthalpy

• energy

• our best friend

• chemical bonds

Tags

NGSS.HS-PS3-1

What is the Law of Conservation of Energy?

• Energy is equal to reactants and products

• Energy can be created nor destroyed

• Energy is used up but it can be replenish

• Energy is conserved and preserved

Tags

NGSS.HS-PS3-2